Coral Reef Baseline Assessment
Understanding our reefs and how to bring them back to life
Concerned about the rapid deterioration of coral reefs adjacent to their coastline in recent decades, a few concerned Mill Reef Club members privately commissioned a coral reef baseline assessment in the fall of 2020. The goals of this assessment were to collect and analyze data on indicators of coral reef health, evaluate environmental conditions and anthropogenic impacts, and provide recommendations for ecosystem restoration. To reach these objectives, marine scientists Genevieve Renaud-Byrne and Molly Wilson conducted surveys at 20 sites along Mill Reef’s coastline, including 6 quantitative sites at which they analyzed benthic (seafloor) composition and reef fish and invertebrate populations.
What we found
Widespread coral loss
Live coral cover ranged from 1% to 22% of total benthic cover, falling below the nearly 40% live coral cover levels found at some of the Caribbean’s more pristine reefs.
High abundance of coral competitors
Algae and other organisms that compete with corals for space and light were abundant throughout the survey area. Algae covered over 75% of the benthos in some sites.
Depleted herbivore populations
Herbivores such as parrotfish and long-spined sea urchins benefit corals by suppressing algae. Low parrotfish biomasses and skewed size distributions observed indicate overfishing, while long-spined urchins were nearly absent.
Opportunities for restoration
Despite the widespread degradation observed throughout the survey area, promising colonies of live corals were also found thriving in local conditions. Based on their survey findings, Genevieve and Molly provided recommendations for an active coral restoration program. They identified several sites that would provide ideal conditions for underwater coral nurseries, where collected coral fragments can grow in monitored environments before being outplanted onto degraded reefs. We are currently pursuing these recommendations through a coral restoration initiative expected to launch in 2021.
Photo credits: Molly Wilson